In many applications, it is desirable for radio frequency (RF) transmit systems to meet spectral performance, out-of-band emissions, and error vector magnitude (EVM), as well as other requirements, starting from an initial power on of the RF transmit system. It is further desirable for RF transmit systems to achieve both high efficiency (e.g., low power consumption) and high signal integrity. One means of improving efficiency in such systems is to utilize an architecture in which an RF power amplifier (PA) of the RF system is switched among a set of operating states. For example, some systems might select (e.g., via switches) a bias voltage of the PAs (e.g. a drain or gate bias voltage of a field effect transistor) in the RF transmit system from among multiple different supply voltages.
Digital pre-distortion (DPD) is sometimes employed to help ensure signal integrity of a signal being transmitted by an RF transmit system while at the same time reducing power consumption of the RF transmit system.